A so-called ink-jet recording method has been put into practical use in which liquid droplets of a recording liquid containing a water-soluble colorant, e.g., a direct dye or an acid dye, are issued from a minute ejection orifice to conduct recording.
With respect to the recording liquid, it is required to be stably ejectable over a long period of time and to rapidly fix to recording papers for general business use, e.g., paper for PPCs (plain-paper copiers) such as electrophotographic paper, and fanfold paper (continuous paper for computers, etc.), to give a print in which the printed characters are of good quality, that is, the printed characters should be free of blurring and have clear contours. The recording liquid is also required to have an excellent storage stability. Therefore, solvents usable in the recording liquid are severely restricted.
Colorants used for the recording liquid are necessary to meet the requirements such that they have sufficient solubility in the solvents which are restricted as described above, that they are capable of stably ejecting the recording liquid over a long period of time, that they are stable even when they are stored for a long period of time, that they can provide printed images having a high density, and that they have excellent water-resistance and light-resistance. However, it has been difficult to satisfy these various requirements at the same time.
In order to meet the above requirements, various methods have been proposed in, for example, JP-A-55-144067, JP-A-55-152747, JP-A-57-207660, JP-A-59-226072, JP-A-61-2776, JP-A-61-57666, JP-A-61-285276, JP-A-62-190269, JP-A-62-190271, JP-A-62-190272, JP-A-62-250082, JP-A-62-246975, JP-A-62-246974, JP-A-62-288659, JP-A-63-8463, JP-A-63-22867, JP-A-63-117079, JP-A-63-30567, JP-A-63-33484, JP-A-63-63764, JP-A-63-105079, JP-A-64-31877, JP-A-1-93389, JP-A-1-210464, JP-A-1-240584, JP-A-2-16171, JP-A-2-140270, JP-A-3-100081, JP-A-3-200882 and JP-A-5-230407 (the term "JP-A" as used herein means an unexamined published Japanese patent application), but recording liquids which sufficiently meet commercial requirements have not been developed.